The objectives of this research are to develop reagents and methods for photolabeling membranes, to apply these methods to neuromembranes, and to study the properties of synaptic vesicles and of synaptic junctional complexes. Methods to be employed include photochemistry, nuclear magnetic resonance (particularly carbon-13 resonance), electron microscopy, and two-dimensional polyacrylamide gel electrophoresis. The significance of the proposed research is in its contributions to the understanding of the structures of biological membranes and the mechanism of release of neurotransmitter at chemical synapses. Neurotransmission is very important in understanding brain function, and knowledge of the fundamental mechanisms is relevant in such medical areas as mental illness. It is hoped that our chemically oriented studies will complement the work of neurobiologists, neurochemists, and pharmacologists, and will contribute to the identification of individual molecules and membrane structures which are important in the process of neurotransmission.